The present invention relates generally to single or multi-cell, lead-acid batteries and in particular, to a method of filling such a battery with electrolyte without damaging the cell pack(s) within the battery and to the design of the battery which incorporates integral deflector surfaces within the battery that are used in the filling process to protect the cell pack(s). Each cell of a single cell or a multi-cell, lead-acid battery of the starved electrolyte type utilizing in situ formation is defined by a compartment which houses a cell pack comprising at least one porous positive plate, at least one porous negative plate, and a porous, relatively fragile, microfiber glass mat separator. Normally, the positive and negative plates are formed of lead grids on which the active material of the plate is affixed by pasting. The cell packs within each compartment are positioned directly beneath filling ports of the compartment through which the electrolyte is introduced into the battery.
A multi-cell, lead-acid battery is filled with electrolyte by drawing a high vacuum on one or more of the battery's cells. After sufficient time has passed to remove all of the air from the porous separator and the porous plates, the acid can either be injected into the cell compartment(s) under pressure or drawn into the cell compartment(s) by the vacuum. The high vacuum causes the electrolyte to rush into the cell compartment(s) through the filling port(s) of the cell(s) with force. Due to the fragile nature of the microfiber glass mat separator(s) in each cell pack and manner in which the positive and negative plates of each cell pack are formed, electrolyte impinging directly on a cell pack can damage the cell pack. The direct impingement of the inrushing electrolyte on the cell pack can damage or displace the fragile, microfiber glass mat separator reducing one of the primary functions of the separator which is to provide separation between the positive and negative electrodes. This will lead to early cell failure due to shorting across the area where the separator was damaged during the filling of the battery. In addition, should the positive and/or negative plates of the cell be exposed to the inrushing electrolyte by damage to and/or the displacement of the microfiber glass mat separator during the filling process, the active material of the plates can be displaced from the lead grids of the plates setting up a shorting path within the cell pack.
Previously, attempts have been made to solve the above problems by placing paper or plastic deflectors on the upper surface of the cell packs. However, this approach to the problem has proved to be only marginally satisfactory. This method of protecting the cell packs during the high vacuum filling operation requires the use of assembly personnel to cut and place the paper deflectors on the cell packs thereby increasing the costs of producing the battery. In addition, the assembly personnel may inadvertently forget to place a paper deflector in each cell compartment or may misplace a paper deflector in one or more of the cell compartments or the paper deflector may shift out of position after placement and prior to the filling operation. Any of these occurrences will expose the cell pack to damage and can result in the problems discussed above.
Thus, there has been a need to provide a method and battery structure which will enable the filling of single cell or multi-cell, lead-acid batteries on an assembly line by drawing a high vacuum wherein the cell packs of the battery do not become damaged during the filling operation.